The present invention relates to tracked vehicles and, in particular, to an improved track drive assembly for all terrain vehicles wherein the assembly height profile is varied with modular drive tooth sprocket rings having offset drive teeth, wherein a support frame guide prevents track dislodgement, and wherein independent, resiliently biased idler wheel rocker arms provide conformal track flexion to encountered obstacles.
A wide variety of personal, passenger and commercial all terrain vehicles have been developed for travel over terrains of all types, including stream and river beds, sand, sodden soil and swamp, rocks, snow and ice. Track assemblies have also been developed for converting wheeled vehicles into track vehicles. For example, track assemblies have been developed by applicant to convert wheeled passenger trucks and wheeled recreational all terrain vehicles (ATV) over to tracked vehicles able to operate over a wider range of terrains and operating conditions.
Conversion track assemblies have also been developed for commercial, industrial and military vehicles that include working attachments such as booms, blades, trenchers, cultivation equipment, mowers, and towed equipment used to perform specific tasks at remote locations. These work vehicles typically support at least two track assemblies from appropriate chassis mounted suspensions; more typically, four track assemblies are used to replace the wheels/tires at each axle. Representative assemblies of the foregoing type developed by applicant are shown at U.S. Pat. Nos. 7,131,508; 6,904,986 and 5,607,210.
Although the foregoing assemblies have proven beneficial, problems are occasionally encountered due to relatively high operating centers of gravity and accommodating operating or transportation height restrictions between work sites. That is, overhanging structures at a work site may prevent vehicle movement beneath the structure. Clearance problems can also exist in relation to bridges, high tension lines etc. during transport, necessitating track removal and re-mounting upon reaching a destination.
Occasionally too the drive tracks can dislodge where terrain conditions present unusual lateral forces that can force the track from the idler wheel and drive sprocket support assembly. Other track issues can also develop where the track is not able to flex and conform sufficiently on exceptionally rough terrain.
The present invention was developed to overcome the foregoing problems. The several different improved track assemblies particularly provide an improved track support assembly wherein the assembly height profile is altered to maintain a height profile at the vehicle that is substantially the same as when using wheels/tires. The height profile is particularly changed via modularly sized, offset drive tooth rings that mount to a supporting drive sprocket hub. Cooperating independent, idler wheel rocker arm suspensions improve track flexion at the track assembly and an associated track guide/retainer plate at the track support frame prevents track dislodgement.